A power source in electronic equipment such as TVs, smart phones or personal computers is required to stably supply a constant DC voltage. A switching power-supply device is used as the power source.
A control IC (Integrated Circuit) used in the switching power-supply device performs a function setting, such as a threshold-value setting operation for determining of switching between standby operation and steady operation at the time of start or the like.
U.S. Pat. No. 9,036,369 discloses technique for generating an identification signal in a control IC by a diode and a resistor externally attached to the control IC when the start of the control IC, and then performing the function setting of the control IC.
US2006/209581 discloses technique for performing the function setting of the control IC by generating a voltage to an external terminal of the control IC with using a resistor or the like and then comparing the generated voltage with a reference voltage.
However, in the two technique, since the dedicated resistor or diode for the function setting are required, a miniaturization and a reduction in cost of the switching power-supply device is hindered.